4Suite is a Python-based toolkit for XML and RDF application development. It features a library of integrated tools for XML processing, implementing open technologies such as DOM, RDF, XSLT, XInclude, XPointer, XLink, XPath, XUpdate, RELAX NG, and XML/SGML Catalogs. Layered upon this is an XML and RDF data repository and server, which supports multiple methods of data access, query, indexing, transformation, rich linking, and rule processing, and provides the data infrastructure of a full database system, including transactions, concurrency, access control, and management tools. It also supports HTTP, RPC, SOAP, and FTP, plus APIs in Python and XSLT.

Apache Jakarta Regexp is a 100% pure Java regular expression package. Expression syntax supports all of Perl5 syntax, with the exception of back reference substitution markers (several people have mentioned this lack, so please feel free to contribute a solution). It also supports a very limited subset of POSIX features. Performance and features are somewhat inferior to ORO, and the new JDK 1.4 (java.util.regex) package, but the package is especially small and features the ability to precompile expressions (without using object serialization) into byte arrays, thus avoiding the need to load the expression compiler.

Apache Jetspeed is an Enterprise Information Portal that allows users to aggregate and organize various information sources and present them in a multi-device, user-customizable Web interface. It integrates a simple syndication system based on OCS and RSS formats.

The Apache JMeter is a 100% pure Java desktop application designed for performance and load testing of servers. It was primarily designed for Web/HTTP testing but it has been expanded to include support for a variety of testing modules. It ships with modules for HTTP and SQL databases (using JDBC). It may be used to test server performance both on static and dynamic resources, to simulate a heavy load on a server or network to test its strength, or to analyse overall performance under different load types. It also provides pluggable interfaces for customizing data visualization, test synchronization, and the construction and execution of tests.

The Apache JServ is a Java servlet engine, an external process written in Java which runs separate from the web server and handles requests to Java servlets. mod_jserv is an Apache HTTPD module written in C which provides an interface to the Apache JServ engine.

When building server side applications for the Web, independently of the language used (Java, PHP, Perl, etc), a lot of time is spent writing embedded HTML code and dealing with the fact that HTTP is a stateless protocol. SPFC allows you to write HTML forms like you write a Java GUI.

Apache-SSL is the original secure webserver based on Apache and SSLeay/OpenSSL. It provides 128 bit encryption, client authentication and a modular API. It is actively maintained, and very widely used.

auth_ldap is an LDAP authentication module for the Apache Web server. Auth_ldap
has excellent performance, due to its use of aggressive client-side caching
algorithms. It also has support for LDAP over SS or TLSL. It also features a
mode that lets Microsoft Frontpage clients manage their Web permissions while
still using LDAP for authentication.

Avalon is Apache's Java Server Framework project. It is separated into
six subprojects: Framework, Excalibur, LogKit, Cornerstone, Phoenix,
and Apps. Its purpose is to simplify server side programming for
Java-based projects. It formalizes several best practices and patterns
for server side programming. Framework describes the interfaces and
contracts for the component-based architecture. Excalibur provides a
number of useful components and utilities. LogKit is a logging
implementation. Cornerstone is a group of reusable server components
and services. Phoenix is an enterprise container implementation that
uses all of the other subprojects to automatically deploy and manage
one or more componentized servers. Apps is a home for several
Phoenix-compatible server applications and reusable components (like
FtpServer).